我们在使用UITabBarController时经常会遇到这种情况:某个页面在用户没有登陆的情况下,点击item需要跳转到登录页面。还可能会要求登录页面从当前的item自下向上显示。其实就是用到了UITabBarControllerDelegate中的一个代理方法。
1.下面开始实现,首先我们创建一个MainTabBarController,实现效果:
2.我们定义一个全局的Bool变量:
//定义一个变量,控制如何跳转
var change: Bool = true
当然,这个变量主要是控制是要UITabBab点击后是不是要按常理显示。O(∩_∩)O哈!
再来一个变量,记录一下上一次点击的index:
//记录上一次的index
var _lastSelectedIndex: NSInteger!
var lastSelectedIndex: NSInteger {
if _lastSelectedIndex == nil {
_lastSelectedIndex = NSInteger()
//判断是否相等,不同才设置
if (self.selectedIndex != selectedIndex) {
//设置最近一次
_lastSelectedIndex = self.selectedIndex;
}
//调用父类的setSelectedIndex
super.selectedIndex = selectedIndex
}
return _lastSelectedIndex
}
override func tabBar(_ tabBar: UITabBar, didSelect item: UITabBarItem) {
//获取选中的item
let tabIndex = tabBar.items?.index(of: item)
if tabIndex != self.selectedIndex {
//设置最近一次变更
_lastSelectedIndex = self.selectedIndex
}
}
下面我们实现代理方法:
func tabBarController(_ tabBarController: UITabBarController, shouldSelect viewController: UIViewController) -> Bool {
if viewController == self.viewControllers![2] {
if change {
self.selectedIndex = _lastSelectedIndex
let login = LoginViewController()
login.tag = 2
let nav = UINavigationController(rootViewController: login)
self.viewControllers![selectedIndex].present(nav, animated: true, completion: nil)
return false
} else {
return true
}
}
return true
}
在controller,我们可以在返回按钮的响应事件里面设置去哪个页面(想去哪儿去哪儿,想干嘛干嘛)
func backClick(sender: UIBarButtonItem) {
if tag == 2 {
//不管从哪也来的,都回首页
NotificationCenter.default.post(name: NSNotification.Name(rawValue: "pushLogin"), object: self, userInfo: nil)
self.dismiss(animated: true, completion: nil)
}
}
如果不设置的话,就是从哪来,回哪去。。。
func backClick(sender: UIBarButtonItem) {
if tag == 2 {
self.dismiss(animated: true, completion: nil)
}
}
效果就是这样:
MainTabBarController的完整代码:
import UIKit
//定义一个变量,控制如何跳转
var change: Bool = true
class MainTabBarController: UITabBarController , UITabBarControllerDelegate {
deinit {
print("MainTabBarController销毁")
}
//MARK: --life cyle
override func viewDidLoad() {
super.viewDidLoad()
// 添加跳转到首页的观察者
NotificationCenter.default.addObserver(self, selector: #selector(pushHome), name: NSNotification.Name(rawValue: "pushLogin"), object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(pushCollection), name: NSNotification.Name(rawValue: "pushCollection"), object: nil)
self.tabBarController?.hidesBottomBarWhenPushed = true
initBaseLayout()
self.delegate = self
}
//MARK: - prinvate methods
//添加视图
func initBaseLayout(){
//主页
let homeVC = HomeViewController()
let homeNav = UINavigationController(rootViewController: homeVC)
let image1 = UIImage(named: "tabbaritem_home_normal")?.withRenderingMode(.alwaysOriginal)
let image1_s = UIImage(named: "tabbaritem_home_select")?.withRenderingMode(.alwaysOriginal)
let item1:UITabBarItem = UITabBarItem(title: "首页", image: image1, selectedImage: image1_s)
item1.tag = 0
homeNav.tabBarItem = item1
//分类
let classVC = ClassifyViewController()
let classNav = UINavigationController(rootViewController: classVC)
let image2 = UIImage(named: "tabbaritem_fenlei_normal")?.withRenderingMode(.alwaysOriginal)
let image2_s = UIImage(named: "tabbaritem_fenlei_select")?.withRenderingMode(.alwaysOriginal)
let item2:UITabBarItem = UITabBarItem(title: "分类", image: image2, selectedImage: image2_s)
item2.tag = 1
classNav.tabBarItem = item2
//收藏
let collectionVC = CollectionViewController()
let collectionNav = UINavigationController(rootViewController: collectionVC)
let image3 = UIImage(named: "tabbaritem_collect_normal")?.withRenderingMode(.alwaysOriginal)
let image3_s = UIImage(named: "tabbaritem_collect_select")?.withRenderingMode(.alwaysOriginal)
let item3:UITabBarItem = UITabBarItem(title: "收藏", image: image3, selectedImage: image3_s)
item3.tag = 2
collectionNav.tabBarItem = item3
//我的
let mineVC = MineViewController()
let mineNav = UINavigationController(rootViewController: mineVC)
let image4 = UIImage(named: "tabbaritem_mine_normal")?.withRenderingMode(.alwaysOriginal)
let image4_s = UIImage(named: "tabbaritem_mine_select")?.withRenderingMode(.alwaysOriginal)
let item4:UITabBarItem = UITabBarItem(title: "我的", image: image4, selectedImage: image4_s)
item4.tag = 3
mineNav.tabBarItem = item4
let tabArray = [homeNav,classNav,collectionNav,mineNav]
self.viewControllers = tabArray
}
//跳转到首页
func pushHome(){
self.selectedIndex = 0
}
//跳转到收藏
func pushCollection() {
self.selectedIndex = 2
}
//MARK: --setter getter
var _lastSelectedIndex: NSInteger!
var lastSelectedIndex: NSInteger {
if _lastSelectedIndex == nil {
_lastSelectedIndex = NSInteger()
//判断是否相等,不同才设置
if (self.selectedIndex != selectedIndex) {
//设置最近一次
_lastSelectedIndex = self.selectedIndex;
}
//调用父类的setSelectedIndex
super.selectedIndex = selectedIndex
}
return _lastSelectedIndex
}
override func tabBar(_ tabBar: UITabBar, didSelect item: UITabBarItem) {
//获取选中的item
let tabIndex = tabBar.items?.index(of: item)
if tabIndex != self.selectedIndex {
//设置最近一次变更
_lastSelectedIndex = self.selectedIndex
}
}
//MARK: -- UITabBarControllerDelegate
func tabBarController(_ tabBarController: UITabBarController, shouldSelect viewController: UIViewController) -> Bool {
if viewController == self.viewControllers![2] {
if change {
self.selectedIndex = _lastSelectedIndex
let login = LoginViewController()
login.tag = 2
let nav = UINavigationController(rootViewController: login)
self.viewControllers![selectedIndex].present(nav, animated: true, completion: nil)
return false
} else {
return true
}
}
return true
}
}